As a method for communication service handover in which a communication service used by a user in a certain device is used continuously in other devices, there are following methods. First of all, there is a method in which SIP (Session Initiation Protocol) module is mounted in a client and a server so as to apply a sequence such as “3rd party call” and “Call Transfer”. Other methods include a method to mount corresponding middleware in a client and a server by independently defining a state description for each service application, a method to introduce a virtual socket between a service application and a BSD socket, and a method to mount a platform such as JAVA (registered trademark) and VMware (registered trademark) so as to transfer to each application.
If a sequence such as “3rd Party Call” and “Call Transfer” is applied as a method for communication service handover, interaction is required between a SIP module and a service application. If middleware with independently defined state description for each service application is mounted, it is similarly necessary to correspond to each service application in addition to require interaction between the middleware and a service application. Also, in the case of introducing a virtual socket, it is necessary to prepare a new service application in which API used for virtual socket is mounted. If a platform such as JAVA (registered trademark) and VMware (registered trademark) is mounted, it is accompanied with necessity of newly preparing a service application in which “JAVA (registered trademark) API” is mounted and necessity of integrally transferring components ranged from OS (Operating System) to applications. Moreover, many methods for the communication service handover require additional mounting on a server side to realize communication service handover.
As a related technique, Japanese Patent Publication JP2005-210378A discloses an application software transition method in multi-computer architecture.
This related technique, which corresponds to one of methods for the communication service handover between clients, is characterized by having a session manager and a network controller in the outside of a device. This related technique, which discloses communication service handover between clients, requires that a device is linked to a session manager and a network controller which are provided in the outside of the device.
Japanese Patent Publication JP-2005-535241A also discloses a session manager.
This related technique, which corresponds to one of methods for communication service handover between servers, is characterized by being based on a cluster technique. This related technique, which discloses communication service handover between servers, is after all a switching technique applied to servers. It is also premised on the presence of cluster software, wherein it is prerequisite to be retrieved from a state in the middle of a session by mounting a checkpoint function for clustering.